Automatic document conveyance device and image reading apparatus using the same

ABSTRACT

An automatic document conveyance device, include a paper guide which has a slot formed by cutting off a part of a conveyance surface for guiding a document; a conveyance unit which inserts in and detach from the slot; wherein the conveyance unit further comprising: a motor which generates driving force; a motor holding part which holds the motor; a driving roller which conveys a document; a drive transmission mechanism which transmits the driving force generated by the motor to the driving roller via a driving roller shaft; and a fitting part which fits the conveyance unit into the slot so that one surface of the conveyance unit forms the conveyance face.

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-089450, filed on Apr. 1, 2009, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present invention relates to an automatic document conveyance device for conveying a document and an image reading apparatus using the automatic document conveyance device.

BACKGROUND ART

An automatic document conveyance device conveys a document to an image reading apparatus. This automatic document conveyance device may have a function to eject the document from the image reading apparatus.

The automatic document conveyance device includes a paper feed tray on which the document before reading is stacked and a document conveyance unit having a mechanism for conveying the document to the image reading apparatus.

On the contrary, in paragraphs [0034] to [0037] of a Japanese Patent Application Laid-Open No. 2007-096936 discloses an image reading apparatus which has a stationary document reading function and an automatic feeding document reading function. This image reading apparatus includes an automatic document conveyance device which automatically conveys the document to a document reading table such as an automatic feeding document reading table or the like. FIG. 8 is a top view of a document conveyance unit for automatically conveying the document that is included in the automatic document conveyance device disclosed in Japanese Patent Application Laid-Open No. 2007-096936. This document conveyance unit includes a paper guide 201, a motor 202, a drive transmission mechanism 203, a driving roller shaft 204, a driving roller 205 and a frame 206.

The paper guide 201 functions as a document conveying path in which the document is conveyed. The motor 202 applies a rotational driving force to the drive transmission mechanism 203. The drive transmission mechanism 203 transmits the rotational driving force to the driving roller shaft 204 to rotate it. The driving roller shaft 204 is disposed inside the paper guide. When the driving roller shaft 204 rotates, the driving roller 205 attached to the driving roller shaft 204 rotates. A part of the driving roller 205 is arranged so as to contact with the document conveying path formed by the paper guide 201. The rotating driving roller 205 applies the driving force to the document conveyed on the document conveying path.

The frames 206 are provided at the both ends of the paper guide 201 to increase the strength of the automatic document conveyance device. The document conveyance unit includes a motor holding part 214 (refer to FIG. 9) for holding the motor 202 and a driving roller shaft holding part (not shown) for holding the driving roller shaft 204. The document conveyance unit further includes an auxiliary roller (not shown) which contacts the outer peripheral surface of the driving roller 205 and pinches the document. And this auxiliary roller follows and rotates to rotation of driving roller 205.

FIG. 9 is a top view of an automatic document conveyance device 211 in which the document conveyance unit shown in FIG. 8 is installed. A document conveyance unit 213 includes the motor 202, the drive transmission mechanism 203, the motor holding part 214, the frame 206, a resist roller shaft 215, a feed roller shaft 216, a feed roller shaft 217 and a document ejection roller shaft 218.

The resist roller shaft 215, the feed roller shaft 216, the feed roller shaft 217 and the document ejection roller shaft 218 correspond to the driving roller shaft 204 shown in FIG. 8 and rotate the resist roller, the feed roller and the document ejection roller, respectively.

A space B in which the drive transmission mechanism 203, the motor 202 and the motor holding part 214 are installed is provided in the document conveyance unit 213 in addition to the document conveying path A for conveying a document 212. An arrow C indicates a conveying direction of the document 212 in the document conveying path A.

Each roller in the document conveyance unit 213 applies the driving force obtained from the motor 202 via the drive transmission mechanism 203 to the document 212 and conveys the document 212 in a document conveying direction C.

However, since the drive transmission mechanism 203, the motor 202, and the motor holding part 214 are provided in the outside of the document conveying path A, a problem to which the width dimension of automatic document conveyance device 211 becomes large at least only space B indicated in FIG. 9 happens them.

The driving roller shaft 204 connected to the motor 202 via the drive transmission mechanism 203 is disposed so as to bridge the frames 206 provided at the both ends of the paper guide 201 as shown in FIG. 8. Since the drive transmission mechanism 203 and the motor 202 are disposed outside the document conveying path A, a length of the driving roller shaft 204 is longer than a distance (which corresponds to the width of the document conveying path A) between the frames 206 placed at the both ends of the paper guide 201. When the length of the driving roller shaft 204 is long, a diameter of the driving roller shaft 204 is made large to ensure strength of the driving roller shaft 204. Accordingly, the increase of the length and the increase of the diameter of the driving roller shaft 204 cause the increase of the production cost of the driving roller shaft 204 and the increase of the weight of the whole automatic document conveyance device 211.

The drive transmission mechanism, the motor, the motor holding part, the driving roller and a driving roller holding part are integrated in the frame of the document conveyance unit and the frame is covered by an outer cover of the device. Therefore, much time is required for maintenance or replacement of the document conveyance unit.

The Japanese Patent Application Laid-Open No. 1994-194906 discloses a document conveyance device in which a plurality of document paper feeding means and document separation means are provided to individually convey a document of a large size and simultaneously conveys the plurality of documents of a small size.

The document conveyance device simultaneously conveys the plurality of documents of a small size correctly at high speed by the plurality of document paper feeding means and the document separation means. When the document of a large size is conveyed, the document can be conveyed while preventing skewing of the document by removing the detachable document separation means excluding a center portion of the document.

However, since a length of each roller shaft has to be almost equal to a width of a document placement section, a size of a detachable unit is set to a size corresponding to the length of each roller shaft. For this reason, the unit can not be shared by the devices whose document conveying path widths are different from each other, for example, a copying machine dedicated to an A3 size document and a copying machine dedicated to an A4 size document. Therefore, the unit has to be produced for each machine.

SUMMARY

A main purpose of the present invention is to provide an automatic document conveyance device whose size and production cost are reduced and in which maintenance of a document conveyance unit can be easily performed.

An automatic document conveyance device, include a paper guide which has a slot formed by cutting off a part of a conveyance surface for guiding a document; a conveyance unit which inserts in and detach from the slot; wherein the conveyance unit further comprising: a motor which generates driving force; a motor holding part which holds the motor; a driving roller which conveys a document; a drive transmission mechanism which transmits the driving force generated by the motor to the driving roller via a driving roller shaft; and a fitting part which fits the conveyance unit into the slot so that one surface of the conveyance unit forms the conveyance face.

BRIEF DESCRIPTION OF THE DRAWINGS

The Exemplary features and advantages of the present invention will become apparent from the following detailed description when taken with the accompanying drawings in which:

FIG. 1 is a sectional view of an automatic document conveyance device according to the present invention.

FIG. 2 is a perspective view of an automatic document conveyance device which viewed from the upper side according to the present invention.

FIG. 3 is a perspective view of an automatic document conveyance device according to the present invention in a state in which the document conveyance unit is dismounted.

FIG. 4 is a top view of a document conveyance unit which is provided in an automatic document conveyance device according to the present invention.

FIG. 5 is an exploded perspective view of a conveyance unit according to the present invention.

FIG. 6A is a perspective view of an upper part of a conveyance unit according to the present invention.

FIG. 6B is a perspective view of a lower part of a conveyance unit according to the present invention.

FIG. 7 is a block diagram of a main part in an automatic document conveyance device according to the present invention.

FIG. 8 is a top view of a document conveyance unit in an automatic document conveyance device according to a related art; and

FIG. 9 is a top view of an automatic document conveyance device which installed a document conveyance unit according to a related art.

EXEMPLARY EMBODIMENT First Exemplary Embodiment

FIG. 1 is a sectional view of an automatic document conveyance device. An automatic document conveyance device 10 is mounted on an image reading apparatus 20. FIG. 2 is a perspective view of the automatic document conveyance device 10 in a state in which a top cover 13 is opened when viewed from the upper side. FIG. 3 is a perspective view showing an automatic document conveyance device in a state in which the document conveyance unit is dismounted. A structure of the automatic document conveyance device 10 will be described with reference to FIG. 1 to FIG. 3.

The automatic document conveyance device 10 is mounted on the image reading apparatus 20. The image reading apparatus 20 is a device such as a copying machine, a facsimile device, a scanner device or the like which reads an image of a document 30 conveyed by the automatic document conveyance device 10. The image reading apparatus 20 includes an image reading unit 21 and a contact glass 22. The image reading unit 21 reads the image of the document 30 that is a read object placed on the contact glass 22.

A document before being read is stacked on a paper feed tray 11. The document 30 after being read is stacked on an ejection paper tray 12. A paper guide 14 as shown in FIG. 2 and FIG. 3 is provided on the top cover 13. A part of the paper guide 14 is cut off. The cut-off portion forms a slot D. As shown in FIG. 3, a mounting groove F having a concave shape is provided on a wall surface of the slot D, and into which a conveyance unit 16 is installed by sliding. An electric contact part 1611 is provided in the conveyance unit 16 and an electric contact part 1401 is provided in the slot D (refer to FIG. 3 or FIG. 5). The electric contact part 1611 physically contacts with the electric contact part 1401 when the conveyance unit 16 is installed in the slot D.

A paper guide 15 that faces the paper guide 14 when the top cover 13 is closed is provided in the automatic document conveyance device 10.

A part of the paper guide 15 is cut off to form a slot E. A mounting groove H having a concave shape is provided on a wall surface of the slot E and a conveyance unit 17 is installed by sliding into the mounting groove H. An electric contact part 1715 as shown in FIG. 6B is provided in the conveyance unit 17 and an electric contact part 1501 as shown in FIG. 3 is provided in the slot E. The electric contact part 1715 is physically contacts with the electric contact part 1501 when the conveyance unit 17 is installed in the slot E.

The conveyance unit 16 and the conveyance unit 17 shown in FIG. 3 are the document conveyance units which can be dismounted from the automatic document conveyance device 10. The conveyance unit 16 conveys the document 30 to a side to which the conveyance unit 17 is installed. The conveyance unit 17 conveys the document 30 conveyed by the conveyance unit 16 to the image reading apparatus 20. An ejection paper guide 18 ejects the document 30 read by the image reading apparatus 20 to the ejection paper tray 12. The ejection paper guide 18 includes a document ejection roller 1801 and a paper ejection auxiliary roller 1802 for ejecting the document 30 to the ejection paper tray 12.

FIG. 4 is a top view of a document conveyance unit of the automatic document conveyance device shown in FIG. 1. A conveyance unit 106 that is the document conveyance unit corresponds to the conveyance unit 16 or the conveyance unit 17 shown in FIG. 3 and includes a motor 102, a drive transmission mechanism shaft 103, a driving roller shaft 104 and a driving roller 105. The conveyance unit 106 is installed in a slot formed by cutting off a part of a paper guide 101.

When the conveyance unit 16 is installed in the slot of the paper guide 101, the continuous surface is formed by a surface of conveyance unit 16 and a surface of the paper guide 101.

FIG. 5 is an exploded perspective view of the conveyance unit 16. FIG. 6A is a perspective view of an upper part of the conveyance unit 17. FIG. 6B is a perspective view of a lower part of the conveyance unit 17.

As shown in FIG. 5, the conveyance unit 16 includes a motor 1601, a drive transmission mechanism 1602, a paper feed roller 1603, a paper feed auxiliary roller 1604, a driving roller shaft holding part 1605, a paper feed roller shaft 1606, a slot installation guide 1607, a motor holding part 1608, a mounting screw 1609, a mounting screw 1610, and the electric contact part 1611. The paper feed roller shaft 1606 is held by the driving roller shaft holding part 1605. The drive transmission mechanism 1602 is fixed to the end of the paper feed roller shaft 1606. The slot installation guide 1607 having a convex shape is provided on a part of the conveyance unit 16. The electrical contact part 1611 for supplying electric power to the motor 1601 and the like is provided in conveyance unit 16. The motor holding part 1608 holds the motor 1601. The driving roller holding part 1605 and the motor holding part 1608 are fixed by the mounting screw 1609.

The conveyance unit 16 with which the driving roller holding part 1605 and the motor holding part 1608 are fixed by the mounting screw 1609 is fixed to the paper guide 14 by the mounting screw 1610.

The conveyance unit 16 is installed in the slot D provided in the paper guide 14 by sliding the slot installation guide 1607 having a convex shape of the conveyance unit 16 into the mounting groove F having a concave shape (refer to FIG. 3). The installed conveyance unit 16 is placed at a position determined by fitting the slot installation guide 1607 into the mounting groove F and fixed to the paper guide 14 by the mounting screw 1610.

A surface shape of an end portion 1612 of the conveyance unit 16 is almost the same as the surface shape of the paper guide 14. As a result, the end portion 1612 of the conveyance unit 16 forms a part of the document conveying path, when the conveyance unit 16 is installed into the slot D. Therefore, when the conveyance unit 16 is installed in the slot D, surface of the conveyance unit 16 and surface of the paper guide 14 forms a continuous surface. When the conveyance unit 16 is installed in the slot D and fixed, the electric contact part 1611 of the conveyance unit 16 physically contacts with the electric contact part 1401 of the paper guide 14 and an electric current flow path is formed.

As shown in FIG. 6A and FIG. 6B, the conveyance unit 17 includes a motor 1701, a drive transmission mechanism 1702, a resist roller 1703, a resist roller shaft 1705, feed rollers 1706 and 1709, feed roller shafts 1708 and 1711, a motor holding part 1712, a driving roller shaft holding part 1713, a slot installation portion guide 1714, the electric contact part 1715 and a mounting screw 1716.

Each of the driving roller shafts (the resist roller shaft 1705, the feed roller shaft 1708 and the feed roller shaft 1711) are held by the motor holding part 1712 and the driving roller shaft holding part 1713. The drive transmission mechanism 1702 is fixed to each of the driving roller shafts. Further, when one driving roller shaft holds a plurality of drive rollers, the size of the conveyance unit 17 is reduced by disposing the drive transmission mechanism 1702 between a plurality of drive rollers.

The motor 1701 is held by the motor holding part 1712. The slot installation guide 1714 which has the convex configuration and the electrical contact part 1715 which supplies the power to the motor 1701 or the like are provided in the side plate of carrying unit 17.

The upper part of the conveyance unit 17 shown in FIG. 6A and the lower part of the conveyance unit 17 shown in FIG. 6B are combined and fixed to the paper guide 15 by the mounting screw 1716.

And as shown in FIG. 3, the conveyance unit 17 is installed in the slot E provided in the paper guide 15. At that time, the conveyance unit 17 is installed by sliding the slot installation guide 1714 having a convex shape of the conveyance unit 17 into the mounting groove H having a concave shape.

The installed conveyance unit 17 is placed at a position determined by fitting the slot installation guide 1714 into the mounting groove H and fixed to the paper guide 15 by the mounting screw 1716.

A shape of a surface 1717 of the upper part of the conveyance unit 17 is almost the same as the shape of the surface of the paper guide 15. Accordingly, when the conveyance unit 17 is installed in the slot E, the surface 1717 of the upper part of the conveyance unit 17 forms a part of the document conveying path which is indicated by a chain double-dashed line in FIG. 1. Therefore, when the conveyance unit 17 is installed in the slot E, one surface of the conveyance unit 17 and one surface of the paper guide 15 form a continuous surface together.

When the conveyance unit 17 is installed in the slot E and fixed, the electric contact part 1715 of the conveyance unit 17 physically contacts with the electric contact part 1501 of the paper guide 15 and an electric current flow path is formed.

Further, in the paper guide 15, in order to enhance the strength of the whole automatic document conveyance device 10, a support member 19 is disposed so as to form a bridge across the document conveying path in the vicinity of the slot E. Namely, the support member 19 which is extended in a lateral direction perpendicular to the document conveying direction is disposed. The support member 19 can be increase strength of the whole automatic document conveyance device.

A shape of a surface 1718 of the lower part of the conveyance unit 17 is almost the same as the shape of a rear surface of the paper guide 15. When the conveyance unit 17 is installed in the slot E, the surface 1718 of the lower part of the conveyance unit 17 forms a part of the document conveying path.

Next, the paper feed operation, the paper conveyance operation, and the paper ejection operation of the automatic document conveyance device shown in FIG. 1 will be described. In the conveyance unit 16, the driving force generated by the motor 1601 is transmitted to the drive rollers such as the paper feed roller 1603 and the paper feed auxiliary roller 1604 of the conveyance unit 16 via the drive transmission mechanism 1602. When the driving roller receives the driving force, it rotates and conveys the document 30 stacked on the paper feed tray 11 to the inside of the automatic document conveyance device 10.

On the other hand, in the conveyance unit 17, the driving force generated by the motor 1701 is transmitted to the drive rollers such as the resist roller 1703, the feed roller 1706 and the feed roller 1709 of the conveyance unit 17 via the drive transmission mechanism 1702. When the drive rollers received the driving force, they rotate and the auxiliary rollers such as the resist auxiliary roller 1704, the feed auxiliary roller 1707 and the feed auxiliary roller 1710 are rotatably driven by friction engagement with an outer peripheral surface of the drive roller.

The document 30 conveyed to the inside of the automatic document conveyance device 10 by the conveyance unit 16 is conveyed on the contact glass 22 of the image reading apparatus 20 by the rotation of the driving roller and the auxiliary roller of the conveyance unit 17. The content of the document 30 conveyed on the contact glass 22 of the image reading apparatus 20 is read by the image reading unit 21.

After this, the document 30 is conveyed in a document conveying direction indicated by the dotted arrow in FIG. 1. By the way, in FIG. 1, a chain double-dashed line PB shows a conveying path on which the document is returned when the content on the back surface of the document is read. Namely, when a double-sided document is read, first, the document is conveyed through the conveying path indicated by the dashed-dotted line PA and the content on the front surface of the document is read. Next, the document is returned through the conveying path indicated by the chain double-dashed line PB. The returned document is conveyed through the conveying path indicated by the dashed-dotted line PA and the content on the back surface of the document is read. The document ejection roller 1801 and the paper ejection auxiliary roller eject the conveyed document 30 to the ejection paper tray 12.

Further, the automatic document conveyance device 10 shown in FIG. 1 has the document ejection roller 1801 apart from the conveyance unit. However, the conveyance unit 17 may include roller such as the document ejection roller 1801 and the paper ejection auxiliary roller.

In order to combine the paper guide and the conveyance unit by using the guide and the slot (for example, the slot installation guide 1607 having a convex shape and the mounting groove F having a concave shape), one of the guide and the slot has to have a concave shape and the other has to have a convex shape. For example, a combination in which the guide having a convex shape is provided in the paper guide and the groove having a concave shape is provided in the conveyance unit is also available.

Second Exemplary Embodiment

Next, an automatic document conveyance device according to the second exemplary embodiment of the present invention will be described. In the automatic document conveyance device of the first exemplary embodiment, the document conveyance unit is composed of the conveyance unit 16 and the conveyance unit 17. In the automatic document conveyance device of the second exemplary embodiment, the document conveyance unit is composed of one conveyance unit.

When the document conveyance unit is composed of one conveyance unit, for example, in the automatic document conveyance device shown in FIG. 1 to FIG. 3, the conveyance unit 16 is not disposed. The paper feed roller and the paper feed roller shaft are disposed in the conveyance unit 17.

In such automatic document conveyance device, because the document conveyance unit can be realized as one detachable conveyance unit, the size of the automatic document conveyance device can be reduced.

Accordingly, the automatic document conveyance device suitable for a copy machine dedicated to a small-sized document or the like can be obtained.

Third Exemplary Embodiment

Next, an automatic document conveyance device according to the third exemplary embodiment of the present invention will be described.

In the automatic document conveyance device of the first exemplary embodiment, the document conveyance unit is composed of the conveyance unit 16 and the conveyance unit 17. In the automatic document conveyance device of the third exemplary embodiment, the document conveyance unit is composed of three or more conveyance units.

When the document conveyance unit is composed of three or more conveyance units, in the automatic document conveyance device shown in FIG. 1 to FIG. 3, for example, the drive rollers (the resist roller 1703, the feed roller 1706 and the feed roller 1709) of the conveyance unit 17 are disposed in the different conveyance units.

Each conveyance unit has a shape of which the conveyance unit can be installed in the slot formed by cutting off a part of the paper guide 14 or the paper guide 15. When each of the conveyance units is installed in the corresponding slot, one surface of the conveyance unit and one surface of the paper guide form a continuous surface together.

The conveyance unit including the document ejection roller 1801 may be individually disposed. In such automatic document conveyance device, the document conveyance unit is composed of three or more detachable conveyance units. Therefore, a size of each conveyance unit can be reduced and a component of the conveyance unit can be shared by an automatic document conveyance device which can be installed to a plurality of devices whose document conveying paths are different from each other. Because each conveyance unit is miniaturized, the maintenance of the component of the conveyance unit can be easily performed.

Further, the above-mentioned configuration of the conveyance unit is one example. Therefore, the driving roller used in the automatic document conveyance device can be disposed in an arbitrary conveyance unit.

In the automatic document conveyance device of the first exemplary embodiment to the third exemplary embodiment, a gear is employed for the drive transmission mechanism. However, a toothed pulley, a timing belt, or the like may be employed for the drive transmission mechanisms.

Fourth Exemplary Embodiment

Next, an automatic document conveyance device according to a fourth exemplary embodiment of the present invention will be described. FIG. 7 is a block diagram showing a main part of an automatic document conveyance device according to the present invention.

As shown in FIG. 7, the automatic document conveyance device includes a conveyance unit 2 (for example, it corresponds to the conveyance unit 16 shown in FIG. 3) which is detachably mounted to a paper guide 1 (for example, it corresponds to the paper guide 14 shown in FIG. 3).

This conveyance unit 2 includes a motor 4 (for example, it corresponds to the motor 1601 shown in FIG. 5) which generates the driving force, a motor holding part 5 (for example, it corresponds to the motor holding part 1608 shown in FIG. 5) which holds the motor 4, a driving roller 6 (for example, it corresponds to the paper feed roller 1603 shown in FIG. 5) which applies the driving force to a document 3 to convey it, and a drive transmission mechanism 8 (for example, it corresponds to the drive transmission mechanism 1602 shown in FIG. 5) which transmits the driving force generated by the motor 4 to the driving roller 6 via a driving roller shaft 7 (for example, it corresponds to the paper feed roller shaft 1606 shown in FIG. 5).

A slot 9 (for example, it corresponds to the slot D shown in FIG. 3) is formed in the paper guide 1 by cutting off a part of the paper guide 1. Fitting portions 41 and 42 (for example, these correspond to the mounting groove F shown in FIG. 3 and the slot installation guide 1607 shown in FIG. 5) which are fitted into each other are provided to the slot 9 and the conveyance unit 2, respectively.

The paper guide 1 and the conveyance unit 2 are formed so that one surface of the paper guide 1 and one surface of the conveyance unit 2 forms a continuous surface together when the conveyance unit 2 is installed in the paper guide 1 by fitting the fitting parts 41 and 42 into each other.

In the automatic document conveyance device having the configuration mentioned above, because the conveyance unit 2 is installed in the slot 9, it is not necessary to newly provide a space in which the components such as the motors 4, the motor holding part 5 and the drive transmission mechanisms 8 are disposed at the outside of the document conveying path.

Accordingly, the size of the automatic document conveyance device can be reduced. The length of the driving roller shaft 7 can be made shorter than the width of the document conveying path. Therefore, the size of the automatic document conveyance device can be reduced in turn.

The conveyance unit 2 can be reliably installed in the paper guide 1 by the fitting parts 41 and 42. When the conveyance unit 2 is installed in the paper guide 1, one surface of the paper guide 1 and one surface of the conveyance unit 2 forms a continuous surface together. Therefore, the smooth document conveying path is secured and improvement of reliability of a document conveyance function can be expected.

The components used for conveying the document can be integrated in the detachable conveyance unit 2. Therefore, the maintenance of the components of the document conveyance unit can be easily performed and maintainability can be improved.

In the exemplary embodiments mentioned above, the following automatic document conveyance devices are disclosed.

(1) The automatic document conveyance device in which the electric contact parts (these correspond to the electric contact part 1401 and the electric contact part 1611) are provided to the conveyance unit 2 and the slot 9, respectively and the electric contact parts are brought into contact with each other when the conveyance unit 2 is installed in the paper guide 1. When such automatic document conveyance device includes a plurality of conveyance units, the current path can be formed between each conveyance unit and the paper guide. Therefore, the electric control can be realized for each conveyance unit.

(2) The automatic document conveyance device in which the conveyance unit 2 includes the driving roller shaft holding part (for example, it corresponds to the driving roller shaft holding part 1605) that holds the driving roller 6 and the driving roller shaft holding part is fixed to the conveyance unit 2 by a screw. In such automatic document conveyance device, the driving roller can be surely fixed to the conveyance unit 2.

(3) The automatic document conveyance device in which one driving roller shaft 7 holds a plurality of drive rollers 6 and the drive transmission mechanism 8 is disposed between one driving roller and the other drive roller. In such automatic document conveyance device, the drive transmission mechanism is disposed between the drive rollers. Therefore, the small-sized conveyance unit can be formed as compared with a case in which the drive transmission mechanism is disposed outside the drive rollers.

(4) The automatic document conveyance device in which a support member (for example, it corresponds to the support member 19) which is extended in a lateral direction perpendicular to the document conveying direction is disposed in the vicinity of the slot 9. In such automatic document conveyance device, the strength of the whole automatic document conveyance device can be enhanced by the support member.

The previous description of embodiments is provided to enable a person skilled in the art to make and use the present invention. Moreover, various modifications to these exemplary embodiments will be readily apparent to those skilled in the art, and the generic principles and specific examples defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not intended to be limited to the exemplary embodiments described herein but is to be accorded the widest scope as defined by the limitations of the claims and equivalents. Further, it is noted that the inventor's intent is to retain all equivalents of the claimed invention even if the claims are amended during prosecution. 

1. An automatic document conveyance device, comprising: a paper guide which has a slot formed by cutting off a part of a conveyance surface for guiding a document; a conveyance unit which inserts in and detach from the slot; wherein the conveyance unit further comprising: a motor which generates driving force; a motor holding part which holds the motor; a driving roller which conveys a document; a drive transmission mechanism which transmits the driving force generated by the motor to the driving roller via a driving roller shaft; and a fitting part which fit into the slot of the conveyance unit so that one surface of the conveyance unit forms the conveyance face.
 2. The automatic document conveyance device according to claim 1, further comprising: electric contact parts which are provided in the conveyance unit and the slot, respectively and brought into contact with each other when the conveyance unit is installed in the paper guide.
 3. The automatic document conveyance device according to claim 1, further comprising: a driving roller shaft holding part which holds the driving roller that is included in the conveyance unit; wherein the driving roller shaft holding part is fixed to the conveyance unit by a screw.
 4. The automatic document conveyance device according to claim 1, wherein one the driving roller shaft holds a plurality of the drive rollers and the drive transmission mechanism is disposed between one driving roller and the other drive roller.
 5. The automatic document conveyance device according to claim 1, wherein a support member which is extending in a lateral direction perpendicular to a document conveying direction is disposed in a vicinity of the slot.
 6. An image reading apparatus, comprising: an image scanner which reads a image of a document; and an automatic document conveyance device which has a paper guide and a conveyance unit; wherein the paper guide has a slot formed by cutting off a conveyance surface for guiding a document; and a conveyance unit cab be inserts in and detach from the slot and has a motor which generates driving force, a motor holding part which holds the motor, a driving roller which conveys a document, a drive transmission mechanism which transmits the driving force generated by the motor to the driving roller via a driving roller shaft, and a fitting part which fits the conveyance unit into the slot so that one surface of the conveyance unit form a conveyance face.
 7. The image reading apparatus according to claim 6, the automatic document conveyance device further comprising: electric contact parts which are provided in the conveyance unit and the slot, respectively and brought into contact with each other when the conveyance unit is installed in the paper guide.
 8. The image reading apparatus according to claim 6, the automatic document conveyance device further comprising: a driving roller shaft holding part which holds the driving roller that is included in the conveyance unit; wherein the driving roller shaft holding part is fixed to the conveyance unit by a screw.
 9. The image reading apparatus according to claim 6, wherein one the driving roller shaft holds a plurality of the drive rollers and the drive transmission mechanism is disposed between one driving roller and the other drive roller.
 10. The image reading apparatus according to claim 6, wherein a support member which is extending in a lateral direction perpendicular to a document conveying direction is disposed in a vicinity of the slot. 